watzmann.blog

I just released Augeas 0.1.1; without really planning it, it turned out that the last two weeks were mostly spend on fixing bugs (besides the regular expression enhancement I blogged about previously — even though the real reason for doing that was that the typechecker had a serious bug, and subtraction of regular languages is needed to make the fixed typecheck usable)

The reference counting code in the interpreter had some serious leaks. I had known about them for a while, but never tried to track them down systematically, partly because I thought it would be way too hairy. As it turned out, they weren't that hard to track down; the key ingredient in squashing them was writing little test scripts that only exercised a small number of operations, like

  let l = key /a/

and then running Valgrind a lot, and gdb a little. Of course, the real trick is to figure out what little toy scripts to write ...

Besides memory leaks, I also realized, using Valgrind's massif tool, that compiled regular expressions are huge, and I was hanging on to them for way too long.

With all that, Augeas 0.1.1 has no known memory leaks, and uses a reasonable amount of memory. Most of the honor for that goes to Valgrind, which is an amazingly useful tool.